This invention relates to foil bearings generally and in particular a variable stiffness mechanism for use with foil bearings.
Foil bearings are used to support light weight, high speed rotors in compressors, turbochargers, turbogenerators, turbine gas generators, cryogenic expanders, blowers, pumps, aircraft aircycle machines, centrifuges, scanners, computer tape drives, yarn spinners and the like.
The advantages of foil bearings are many and include:
(a) stability at high operating speeds without the harm of destruction at the onset of self excited whirl and the capacity to traverse two or more critical speeds with ease; PA1 (b) capability of operating at extreme temperatures ( high temperatures for gases and low temperature for cryogenic liquids) and in the presence of thermal gradients; PA1 (c) ability to accommodate misalignment, manufacturing inaccuracies and differential expansion of bearing components; PA1 (d) possession of inherent damping, flexibility and good wipe-wear characteristics; and PA1 (e) tolerance of contaminants and abrasive particles.